An anonymous commenter wanted me to post this, and I think he makes a few great points:

Cycling century rides have 50% (+/-) female participation, running races from 5K to marathon often have more women than men and triathlons have enough female participation to warrant major women-only tri's. So what is it about bike racing that is such a disincentive for female participation compared to these other endurance sports that, on the surface, would seem to appeal to the same type of athlete? Has anybody studied this? If so, I've never seen it. One thing is certain, women are not men -- so treating them as though they are just a slower men's class will frustrate the women, the promoters and even a fair number of the men competitors. I'm on dangerous ground here I know, but women are not generally inspired by the same emotional stimuli as men . THERE ARE EXCEPTIONS, but we all know certain things appeal more to men them women, and vice-versa (how many guys do you know that saw the Mamma Mia or Twilight movies multiple times?). The ultimate problem may be that, for whatever reason, bike racing may only be appealing to the minority of the general female population that are those exceptions. If that's the case, then we need to be asking women endurance athletes who DON"T race bikes how to increase the fields. I'm NOT saying that we need to make the sport cute or pretty (mud runs draw plenty of women competitors). I'm making the point that there are a LOT of women endurance athletes in America, maybe we should find out why THEY aren't racing bikes to better understand what needs to be done.

Actually, Emma White is a top level amateur. Additionally, Simon Burney and Adam Myerson spoke as coaches, and their opinions are focused on amateur racers! Maybe we will do a follow up with more top level amateurs if people are interested in hearing about more on run training. Personally, I whole-heartedly agree that running will toughen you up- love it! @TravisBook

That's really interesting, I'm glad you have more insight than my doctor at the time did... he just saw the numbers, didn't know what they meant. Unfortunately my insurance now is terrible so I can't figure anything more out until it improves a bit... @topherfox